We were at WL from Feb 28-24 and thought the buses did pretty good!
For MK we took the boat so I can't speak to that....in general the buses ran GREAT! I will say that we had one night (Friday) where MK was closing at 7pm and we had 645 ADR at BOG, so when we left the park it was 8:15pm and they had already shut down the boats and we had to catch a bus....which was fine but surprising..
For DS, heading there for dinner, we waited almost 30 minutes which was frustrating...
For HS with a 9am opening, we think we missed the first bus, and boarded a bus about 8amish -we should have been waiting at the bus stop by 7:40 but that just didnt happen..BUT we got right to HS, and it was like 8:20ish - and they already opened the gates, and we breezed thru temp check, bag check and rode MMRR and SD by 9am! So, even though we started off slow, we had a winner day! Oh, and I had no trouble getting BG 32 for ROTR using the WIFI @ WL....
For Epcot, we were out there by 9:45ish and got right on a bus and arrived at Epcot by a few minutes after 10am and they were not letting in folks yet - but were at the front of the turnstiles! Let us in like 10:15ish/10:20ish..and we all headed to TT but it was down (didnt come up until close to 12pm) and instead rode Frozen 2xs before the line got ridiculous - and it stayed that way the rest of the day. HOWEVER, we were at Epcot on Sunday, Feb. 21st which was the 2nd to last day of the International Art Festival and the day was kinda busy...
For AK - we got on the first bus (we think) and it was an 8am opening - we were there and on a bus by 7:30am and right to AK - breezed thru temp check and bag check and the park was open but just barely bc folks were still walking back to FOP to form a line and we joined in and by 9am had ridden FOP and Na'vi - which for some reason had a pretty long wait all day. And IF you want to ride FOP they are seating parties next to each other (when we were there in Dec they were skipping a Banshee) but you CAN ask to have a space and we did!
We had a great time! Let me know if you have any other questions!